Polyrotaxane including a cyclic molecule, a linear molecule threading through a cavity of the cyclic molecule in a skewered manner, and capping groups that cap both ends of the linear molecule has specific viscoelastic characteristics and the like, and therefore is expected to be used in various fields. For reflecting the specific viscoelastic characteristics of polyrotaxane to a material, the use of polyrotaxane as a crosslinking agent is considered.
As a material containing polyrotaxane as a crosslinking agent, Patent Literature 1 discloses a urethane elastomer having a low permanent strain, a low stress relaxation property, and a low hysteresis loss.
Patent Literature 2 discloses an adhesive having both a high stress relaxation property and a high holding force due to crosslinkage between a (meth)acrylic ester copolymer having a hydroxy group and polyrotaxane. In the crosslinkage, hydroxy groups in polyrotaxane and in a (meth)acrylate copolymer are used as reaction points. Commonly, hydroxy groups hardly react with each other directly, and therefore are chemically bonded to each other through a polyfunctional isocyanate.